1. Field of the Invention
The present invention relates to a sense circuit for integrated circuits to provide on-chip thermal shutdown and an indication of a thermal fault.
2. Description of the Prior Art
The drive towards higher levels of circuit integration levels in integrated circuit (IC) technology has resulted in IC devices which have greater power density levels than ever before. ICs which consume ten watts of power or more are now increasingly becoming the rule rather than the exception. In the event of certain system faults, there is the exposure with these devices that the temperature of the device will exceed the limit beyond which catastrophic device damage may occur. Fault conditions of this type may include the sudden loss of system cooling capability or the unanticipated obstruction of the flow of device cooling medium.
There is also the case of dedicated line driver chips which must be designed to tolerate line fault conditions whereby the driver outputs are inadvertently shorted to the system power supplies. Under these conditions, there is again the exposure that the device temperature will rise above the limit beyond which catastrophic damage occurs.
A circuit that continuously monitors the junction temperature of an IC and senses when a preset limit has been reached would therefore have several advantages. First, the IC may be shut down in the event of a fault so as to avoid catastrophic device damage. Second, by providing a system flag for the shutdown event, it would be possible to notify the system of the existence of the fault condition so that corrective action could be taken.